// SPDX-License-Identifier: GPL-2.0-only
#pragma once

#include <linux/rtmutex.h>
#include <linux/atomic.h>

#define READER_BIAS (1U << 31)
#define WRITER_BIAS (1U << 30)

struct rwbase_rt
{
	struct rt_mutex_base rtmutex;
	atomic_t readers;
};

#define __RWBASE_INITIALIZER(name)                            \
	{                                                         \
		.readers = ATOMIC_INIT(READER_BIAS),                  \
		.rtmutex = __RT_MUTEX_BASE_INITIALIZER(name.rtmutex), \
	}

#define init_rwbase_rt(rwbase)                       \
	do                                               \
	{                                                \
		rt_mutex_base_init(&(rwbase)->rtmutex);      \
		atomic_set(&(rwbase)->readers, READER_BIAS); \
	} while (0)

static __always_inline bool rw_base_is_locked(const struct rwbase_rt *rwb)
{
	return atomic_read(&rwb->readers) != READER_BIAS;
}

static __always_inline bool rw_base_is_write_locked(const struct rwbase_rt *rwb)
{
	return atomic_read(&rwb->readers) == WRITER_BIAS;
}

static __always_inline bool rw_base_is_contended(const struct rwbase_rt *rwb)
{
	return atomic_read(&rwb->readers) > 0;
}
